"Gain-Scheduled Speed Control of Induction Motor Drives Under Maximum Torque Per Ampere for Airborne Wind Energy Systems"

"This paper presents a single-input single-output (SISO) reformulation of the speed control problem for induction motor drives operating under the maximum torque per ampere (MTPA) constraint. Enforcing MTPA as a structural control law reduces the conventional two-input field-oriented control plant to a single-variable system whose linearized transfer function is analytically derived. The resulting second-order plant exhibits two real poles and a real zero at exactly twice the rotor flux pole frequency. A gain-scheduled proportional-integral controller whose proportional gain is inversely proportional to the stator current magnitude cancels the operating-point dependence of the plant gain, maintaining a constant crossover frequency and phase margin across the entire operating range with only two analytically derived tuning parameters and no flux observer or lookup table. Four strategies\u2014standard field-oriented control, fixedgain MTPA, the proposed SISO-MTPA, and a loss-minimization benchmark\u2014are compared through simulation and experimental validation on an 18.5 kW induction motor under airborne wind energy pumping cycles. The SISO-MTPA reduces stator copper losses by 55% and cuts maximum speed deviation during load transients by >60% in experiments under a realistic airborne wind energy pumping cycle, while uniquely maintaining MTPA efficiency with load-invariant closed-loop bandwidth."